ix] Doctrines of Respiration. 253 



It will be observed that Lagrange's view is the modern 

 view, except that we have since learnt that the oxidation 

 takes place, not in the blood itself, but in the elements of 

 the tissue outside the blood channels. Yet this view was not 

 accepted by all, or even generally, for some time. For many 

 years Lavoisier's view, or rather Sequin's, held its ground. 

 Even the hypothetical hydrocarbonous fluid was accepted, 

 though some, while still maintaining that the oxidation took 

 place in the lungs, supposed that the carbon and hydrogen 

 were oxidised while still in the blood of the pulmonary vessels, 

 and did not need any preliminary secretion into the pulmonary 

 passages. 



The acute Spallanzani, laying hold of Lavoisier's discoveries 

 so soon as they were made known, devoted much time during 

 the latter years of his life to numerous experiments on the 

 respiration of animals, both vertebrate and invertebrate ; the 

 memoirs embodying the results which he had obtained were not 

 published however until after his death, namely in 1803. In 

 addition to many valuable observations as to the effects of cir- 

 cumstances and environment, such as temperature, hybernation 

 and the like on the respiratory process, these memoirs contain 

 two far-reaching conclusions. The one is that the tissues, like 

 the body as a whole, respire, that is to say consume oxygen and 

 produce carbonic acid ; the other is that animals (snails) placed 

 in an atmosphere of hydrogen or nitrogen give out carbonic 

 acid in the same way that they do in common air. 



These results really overthrew Lavoisier's theory of a hydro- 

 carbonous secretion ; but they failed to produce their proper 

 effect, even when put forward in a more complete form many 

 years later, in 1823, by W. F. Edwards in his striking essay, 'The 

 influence of physical agents on life.' The view that oxidation 

 took place in the lungs, and not in the body generally, continued 

 to hold its own, mainly for the reason that, owing to imperfect 

 experimental methods, the various attempts made to shew that 

 blood, as demanded by Lagrange's theory, contained on the one 

 hand oxygen and on the other hand carbonic acid gas, fell short 

 of decisive results. It was not until 1837 when Gustav Magnus, 

 making use of the mercurial air-pump, definitely proved that 

 both venous and arterial blood contained both these gases, 



